Re: extending std::numeric_limits

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 7 Mar 2007 11:35:17 -0500
Message-ID:
<esmpk6$mgs$1@news.datemas.de>
jamesrjones@gmail.com wrote:

On Mar 7, 10:12 am, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:

..
template<class T, class U, class V>
class numeric_limits<DecimalType<T,U,V> > {
    // extensions go here

};

V


This would work fine if DecimalType were a template. But it isn't.
What I have is this (for example):

template < class T, class U >
class fast_model_of_decimals {};

template < class T, class U >
class small_model_of_decimals {};

template < class T, class U >
class other_model_of_decimals {};

I could do this:

template < class T, class U >
class numeric_limits< fast_model_of_decimals< class T, class U > > {};

... and so on for the other models.


That's what you should (or have to) do.

But what I'd like to do is something like this:

template <typename T>
class numeric_limits< T > {};

where T must be a model of a decimal type.


You cannot do that because that is not a specialisation.

Note: I'm using BOOST and I'm familiar with enable_if, which works
great but doesn't quite seem to fit this application. I have a type
trait template is_decimal_type which returns true if the type is a
model of a fixed decimal type and false otherwise.


Just bite the bullet and specialise it for each of your templates.

V
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